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    Using Euro coins as weights (2004)

    (www.rubinghscience.org)
    180 points Tomte | 11 comments | 20 Oct 24 10:18 UTC | HN request time: 1.048s | source | bottom
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    rchowe ◴[20 Oct 24 12:11 UTC] No.41894824[source]▶
    I built a computer vision device that used the top-down area of a penny as a calibration standard. Coins are useful, easy-to-get items that have relatively tight manufacturing tolerances.
    replies(2): >>41894944 #>>41895122 #
    1. cassepipe ◴[20 Oct 24 12:35 UTC] No.41894944[source]▶
    What about wear ? Were they only new coins ?
    replies(3): >>41894957 #>>41895107 #>>41895171 #
    2. Retric ◴[20 Oct 24 12:37 UTC] No.41894957[source]▶
    I’ve never seen significant ware on a coin in circulation.

    Have you?

    replies(4): >>41895028 #>>41895428 #>>41897412 #>>41898161 #
    3. seqizz ◴[20 Oct 24 12:49 UTC] No.41895028[source]▶
    I've seen enough wear to prevent them to be calibration material at least.
    replies(2): >>41895157 #>>41895266 #
    4. wongarsu ◴[20 Oct 24 13:03 UTC] No.41895107[source]▶
    Ever since coin clipping got out of hand in the 1700s most coins feature milled edges or edge inscriptions. They make the edges more resistant to wear and make any wear easy to spot.

    Of course there's a limit to the precision you can get from coins, but considering the scale of their production and the account of handling they see they are surprisingly good

    replies(1): >>41895490 #
    5. ◴[20 Oct 24 13:13 UTC] No.41895157{3}[source]▶
    6. rchowe ◴[20 Oct 24 13:15 UTC] No.41895171[source]▶
    Our area measurement application did not require that tight a tolerance (we were estimating yield on broken material). If I needed that tight a tolerance, I could have gotten proof coins from the mint, or potentially switched to using a real calibration standard like a gauge block.
    7. MadnessASAP ◴[20 Oct 24 13:33 UTC] No.41895266{3}[source]▶
    Depends on what your tolerances are. If you only need to be within a mm a coin is going to beat that by an order of magnitude.

    We use a pack of cigarettes as a gauge for one of the jobs we do. Quick, (not so) cheap, and readily available. May have to standardize on a vape though in the near future.

    8. swores ◴[20 Oct 24 14:02 UTC] No.41895428[source]▶
    I have often, though I suspect not enough to make a significant difference to someone who is already OK with the slight variance between un-worn coins.
    9. rrr_oh_man ◴[20 Oct 24 14:11 UTC] No.41895490[source]▶
    > in the 1700s

    It's been happening since ever.

    10. xboxnolifes ◴[20 Oct 24 18:24 UTC] No.41897412[source]▶
    I have coins that originally had milled edges that are now completely smooth.
    11. fanf2 ◴[20 Oct 24 20:13 UTC] No.41898161[source]▶
    Only on counterfeit £1 coins, before the coins were redesigned to make them harder to fake